... Chemistry according to production requirements. The new molecules were functionalized, as dienophile- or diene compounds by coupling to the glycine’s N-terminus, as originally described by ... carried out as documented by Reppe [16]. The reaction to tetracy-clo-[5.4.21,7.O2,6.O8,11]3,5-dioxo-4-aza-9,12-tridecadiene 4-yl acetyl acid chloride is described by Wiessler [15]. 2. The ... with 2N sulfuric acid, followed by water and acetone. The bis2,6-[5-carboxylic acid-pyrid-2-yl]-dihydrotetrazine 5 (orange colored) could not be purified by recrystal-lisation but was pure...